An Integrated Microfluidic Cryo-Cooling System for MR Microcoils

描述(申请人提供)：将开发一种低温微流控冷却系统，该系统可以在不影响成像表面温度的情况下将磁共振表面线圈冷却到液氮温度，同时保持线圈与目标样本之间的最小距离以实现最高灵敏度。用于提高线圈灵敏度的传统低温恒温器在线圈和样品之间需要厚厚的绝缘层，不适用于通常具有相对较浅穿透深度的表面线圈。因此，低温冷却系统可以使表面线圈和样品紧密接近，以获得最大的线圈灵敏度，可以防止与厚恒冷器相关的信噪比损失，因此提供比未冷却线圈高得多的信噪比。微制造技术将被用来开发一种集成表面线圈的微流控冷冻系统，用微量(纳升)的液氮来冷却线圈。将评估所开发系统的表面线圈和成像表面的温度分布，然后表征导体长度和几何形状的参数空间。还将描述将系统并行化到表面线圈阵列的能力。该系统将使用核磁共振进行评估和优化，并将冷冻冷却的表面线圈与未冷却的表面线圈进行比较。如果成功，这将使平面表面微线圈能够冷冻冷却，用于高分辨率生物样本成像，而不需要厚重的传统低温恒温器。由此产生的系统预计将在信噪比(SNR)方面提高5倍以上，并有可能在不损失图像质量的情况下将扫描时间减少25倍。拟议研究的意义在于，所产生的系统可以为当前的成像需求提供关键工具，例如通过使用高密度表面线圈阵列对小目标(例如单个细胞)进行成像，或者使用超快成像来监测生物样本(如血管或脑片)的实时生理变化。开发的微流控冷冻冷却技术不仅限于特定的表面线圈配置，而且可以广泛应用于各种其他平面和非平面微线圈配置。这项工作可以进一步扩展到使用液氮冷却高温超导(HTS)表面线圈阵列，以在不影响待成像生物样本的情况下进一步提高扫描时间。该项目旨在开发一种集成了磁共振表面线圈的微流控冷冻冷却系统，用于生物样品的高分辨率磁共振成像。

DESCRIPTION (provided by applicant): A cryogenic microfluidic cooling system that can cool MRI surface coils to liquid nitrogen temperature without affecting the temperature at the imaging surface, while maintaining minimal distance between the coils and the target samples for maximum sensitivity will be developed. Conventional cryostats used to improve coil sensitivity require a thick insulating layer between the coil and the sample and are not applicable to surface coils that typically have relatively shallow penetration depth. Therefore, a cryogenic cooling system that can keep the surface coil and the sample in close proximity for maximum coil sensitivity can prevent the SNR loss associated with thick cryostats and therefore provide significantly higher SNR than un-cooled coils. Microfabrication technology will be used to develop a microfluidic cryo-cooling system with integrated surface coils to cool the coil with minute (nanoliter) amount of liquid nitrogen. Temperature profiles at the surface coil and the imaging surface of the developed system will be evaluated followed by characterizing the parameter space of conductor length and geometry. The ability to parallelize the system to surface coil arrays will be also characterized. The system will be evaluated and optimized using MRI and the cryo-cooled surface coils will be compared to un-cooled surface coils. If successful, this will enable cryo-cooling of planar surface microcoils for high-resolution biological sample imaging without the need for a thick conventional cryostat. The resulting system is expected to have an improvement of a factor over 5 in signal-to-noise ratio (SNR) with a potential to reduce scan time by a factor of 25 with no loss in image quality. The significance of the proposed research is that the resulting system can provide critical tools for the current imaging needs, such as imaging small targets (e.g. single cells) by using high-density surface coil arrays or ultra-fast imaging for monitoring real-time physiological changes in biological samples such as blood vessels or brain slices. The developed microfluidic cryo-cooling technology is not limited to a specific surface coil configuration but can be applied broadly to various other planar and non-planar microcoil configurations. This work can be expanded further to cool high temperature superconducting (HTS) surface coil arrays using liquid nitrogen to further improve scanning time without affecting the biological samples to be imaged. This project seeks to develop a microfluidic cryo-cooling system integrated with MR surface coils for high- resolution MR imaging of biological samples.